A senior UN nuclear watchdog official said Iran needed to give his inspectors access to information, people and sites as he began a two-day meeting with Iranian officials on the Islamic state’s disputed atomic activities on Monday.

Herman Nackaerts, deputy director general of the International Atomic Energy Agency (IAEA), told reporters as he arrived at an Iranian diplomatic mission in Vienna that Iran should now engage on issues of substance with the UN agency, which is investigating suspicions that Tehran may be seeking nuclear weapons capability.

“The aim of our two days is to reach agreement on (an) approach to resolve all outstanding issues with Iran, in particular clarification of the possible military dimensions remains our priority,” Nackaerts said.

On Sunday, an image was revealed by The Associated Press which was said to come from inside an Iranian military site and shows an explosive containment chamber of the type needed for nuclear arms-related tests that UN inspectors suspect Tehran has conducted at the site. Iran denies such testing and has neither confirmed nor denied the existence of such a chamber.